Block 2: Autocoids: Histamine

Front 1

How is histamine made?

Back 1

histidine -> (histidine decarboxylase) -> histamine

Front 2

Where in the body is histamine in highest concentrations?

Back 2

lung
skin
stomach
gut

Front 3

Name three places where histamine is stored?

Back 3

mast cells (tissue phagocytes) and basophils (blood phagocytes)
CNS
mucosal layer of GI tract

Front 4

The histamine content of most tissues is related to their ... content?

Back 4

mast cell content

Front 5

Why is histamine inert in mast cells?

Back 5

its stored in secretory granules and linked to proteoglycans

Front 6

How does histamine negatively modulate its own release?

Back 6

through H2 receptors on mast cells

Front 7

When the histamine content of mast cells is depreciated, how long does it take for the concentration to return to normal

Back 7

it can take weeks

Front 8

Are allergic reactions causing histamine release cytolytic?

Back 8

no

Front 9

Name 5 chemicals that cause chemical histamine release

Back 9

morphine
tubocurarine
succinylcholine
vancomycin (red man syndrome)
radiocontrast

Front 10

are chemicals causing histamine release cytolytic?

Back 10

no

Front 11

is energy required for histamine release mediated cellular injury

Back 11

no

Front 12

Give 5 states in which symptoms from histamine toxicity (headache, flushing, hypotension, and nausea) are also seen

Back 12

1. mastocytosis
2. myelogenous leukemia
3. gastric carcinoid tumors
4. food poisoning from spoiled scombroid fish
5. red wine consumption when people have reduced ability to degrade histamine

Front 13

What superfamily of receptors do histamine receptors belong to

Back 13

7 transmembrane G protein-linked receptors

[like rhodopsin ;)]

Front 14

receptor in sm mm, endothelium and brain
signals PLC --> IP3, DAG, NO, and PLA

Back 14

H1

Front 15

receptor in gastric mucosa, brain, cardiac muscle, mast cells
signals cAMP, inhibition of arachidonic acid release, Ca

Back 15

H2

Front 16

receptor in presynaptic, brain, myenteric plexus, peripheral neurons
signals Ca, inhibits cAMP

Back 16

H3

Front 17

receptor in bone marrow, peripheral hematopoietic cells
signals Ca, inhibits cAMP

Back 17

H4

Front 18

through what histamine receptors is vasodilation mediated?

Back 18

H1: endothelial cells
H2: vascular sm mm

Front 19

through what histamine receptors is increased cardiac contractility and increased pacemaker rate mediated?

Back 19

H2

Front 20

Through what histamine receptor is contraction of intestinal sm mm and increased GI motility mediated?

Back 20

H1

Front 21

Histamine receptor involved with bronchoconstriction

Back 21

H1

Front 22

What may happen in anaphylactic pregnant women?

Back 22

may abort due to uterine contraction

Front 23

Histamine receptor involved in stimulant of sensory nerve endings- pain and itching

Back 23

H1

Front 24

Histamine receptor involved in stimulant of gastric acid secretion from parietal cells?

Back 24

H2

Front 25

Histamine receptor involved in triple wheal and flare response to intradermal histamine injection

Back 25

H1

Front 26

Name a physiologic antagonist that acts through a different receptor and opposes action of histamine?

Back 26

epinephrine

Front 27

Name two drugs that can inhibit histamine release from mast cells?

Back 27

cromolyn
nedocromil

Front 28

histamine receptor antagonists act at which receptors?>

Back 28

H1 and H2, they are competitive

Front 29

Describe first generation antihistamines

Back 29

small --> cross BBB
cross react w/ other receptors
available OTC
sedation as side effect

Front 30

Describe second generation antihistamines

Back 30

larger and lipophobic
more specific for H1
prescription only (except Claritin)
non-sedating

Front 31

chlorpheniramine (chlortrimeton)

Back 31

1st generation antihistamine

Front 32

clemastine

Back 32

1st generation antihistamine

Front 33

dimenhydrinate
(dramamine)

Back 33

1st generation antihistamine

Front 34

diphenhydramine

Back 34

1st generation antihistamine
(benadryl)

Front 35

doxylamine

Back 35

1st generation antihistamine

Front 36

hydroxine

Back 36

1st generation antihistamine

Front 37

meclizine

Back 37

1st generation antihistamine
(antivert)

Front 38

promethazine
(phenergan)

Back 38

1st generation antihistamine

Front 39

fexofenadine

Back 39

2nd generation antihistamine
(allegra)

Front 40

cetirizine

Back 40

2nd generation antihistamine

Front 41

loratadine

Back 41

2nd generation antihistamine
(claritin)

Front 42

Name two antihistamines used for sleep induction

Back 42

diphenhydramine
doxylamine

Front 43

only antihistamine approved antitussive

Back 43

diphenhydramine

Front 44

antihistamine most widely used for Parkinson's disease

Back 44

diphenhydramine

Front 45

three antihistamines to treat vertigo/motion sickness

Back 45

meclizine (Antivert)
promethazine (Phenergan)
dimenhydrinate (Dramamine)

Front 46

When do antihistamines reach peak plasma concentration
When do antihistamines reach peak effectiveness

Back 46

2 hrs after oral administration

5-7 hrs after oral administration

Front 47

All 1st generation and most 2nd generation antihistamines are metabolized by which hepatic cytochrome?

Back 47

P450

Front 48

Who eliminates antihistamines faster- adults or kids?

Back 48

kids

Front 49

Name two 2nd generation antihistamines taken off the market

Back 49

astemizole (hismanal)
terfenadine (seldane)

Front 50

Name two antihistamines thought to be of lower risk to take during pregnancy

Back 50

dimenhydrinate
loratadine

Front 51

Name four H2 receptor antagonists

Back 51

cimetidine (tagamet)
famotidine (pepcid)
nizatidine (axid)
ranitidine (zantac)